You have 50 amps available on 1 leg with that configeration or 6,000 watts. What you also have is potential fire. You are potentially supplying 50 amps down a cord rated for 30 amps with 50 amp breakers on both ends so the cord is not protected
I highly recommend you stop this practice. What you are doing is different than an individual with 30 amp service using a 50-30 adapter to plug into 50 amp outlet, this 30amp service trailer has a 30 amp breaker so that protects the cord. That is not true for what you are doing because there is a 50 amp breaker on both ends. With your trailer if you are going to use the 30 amp cord plug into 30 amp service, never 50 amp.